[Phase 3 Trial of RNAi Therapeutic Givosiran for Acute Intermittent Porphyria]

Recent applications of RNA therapeutic in clinics

Ribonucleic acid (RNA) therapy has been extensively researched for several decades and has garnered significant attention in recent years owing to its potential in treating a broad spectrum of diseases. It falls under the domain of gene therapy, leveraging RNA molecules as a therapeutic approach in medicine. RNA can be targeted using small-molecule drugs, or RNA molecules themselves can serve as drugs by interacting with proteins or other RNA molecules. While several RNA drugs have been granted clinical approval, numerous RNA-based therapeutics are presently undergoing clinical investigation or testing for various conditions, including genetic disorders, viral infections, and diverse forms of cancer. These therapies offer several advantages, such as high specificity, enabling precise targeting of disease-related genes or proteins, cost-effectiveness, and a relatively straightforward manufacturing process. Nevertheless, successful translation of RNA therapies into widespread clinical use necessitates addressing challenges related to delivery, stability, and potential off-target effects. This chapter provides a comprehensive overview of the general concepts of various classes of RNA-based therapeutics, the mechanistic basis of their function, as well as recent applications of RNA therapeutic in clinics.

Novel Pharmacological Approaches in the Treatment of Hypertension: A Focus on RNA-Based Therapeutics

Hypertension remains the leading cause of cardiovascular disease and premature death globally, affecting half of US adults. A high proportion of hypertensive patients exhibit uncontrolled blood pressure (BP), associated with poor adherence, linked to pill burden and adverse effects. Novel pharmacological strategies are urgently needed to improve BP control. Dysregulation of the renin-angiotensin system increases BP through its primary effector, Ang II (angiotensin II), which results in tissue remodeling and end-organ damage. Silencing liver angiotensinogen (the sole source of Ang II) has been achieved using novel RNA therapeutics, including the antisense oligonucleotide, IONIS-AGT (angiotensinogen)-LRX, and the small-interfering RNA, zilebesiran. Conjugation to N-acetylgalactosamine enables targeted delivery to hepatocytes, where endosomal storage, slow leakage, and small-interfering RNA recycling (for zilebesiran) result in knockdown over several months. Indeed, zilebesiran has an impressive and durable effect on systolic BP, reduced by up to 20 mm Hg and sustained for 6 months after a single administration, likely due to its very effective knockdown of angiotensinogen, without causing acute kidney injury or hyperkalemia. By contrast, IONIS-AGT-LRX caused less knockdown and marginal effects on BP. Future studies should evaluate any loss of efficacy relating to antidrug antibodies, safety issues associated with long-term angiotensinogen suppression, and broader benefits, especially in the context of common comorbidities such as type 2 diabetes and chronic kidney disease.

[Porphyria]

Porphyrien werden durch Enzymdefekte der Hämbiosynthese hervorgerufen und anhand spezifischer biochemischer Muster von Porphyrinen und deren Vorläufern in Urin, Stuhl und Blut diagnostiziert. Das jeweilige Muster der akkumulierten Porphyrine, Vorläufer und Derivate ist verbunden mit der klinischen Ausprägung, die abdominale, neurologische, psychiatrische, endokrine, kardiovaskuläre Symptome, Leberschaden und/oder Lichtempfindlichkeit der Haut umfassen kann. Klinisch werden akute und nichtakute Porphyrien unterschieden. Bei symptomatischen (klinisch aktiven), akuten hepatischen Porphyrien – hierzu gehören akute intermittierende Porphyrie, Porphyria variegata, hereditäre Koproporphyrie und Doss-Porphyrie – kommt es aufgrund einer Regulationsstörung zur Kumulation der Porphyrinvorläufer 5‑Aminolävulinsäure und Porphobilinogen. Bei den nichtakuten Formen – u. a. Porphyria cutanea tarda, erythropoetische und X‑chromosomale Protoporphyrie sowie kongenitale erythropoetische Porphyrie – führen akkumulierte Porphyrine zu Lichtempfindlichkeit (Fotodermatose) und mitunter auch zu schweren Leberschäden. Zur Therapie der Porphyrien stehen sowohl bewährte und sichere als auch innovative Optionen zur Verfügung.